It is well known that a transit vehicle has one or more openings or doorways through which passengers can enter and exit the vehicle. For a vehicle with more than one doorway, the openings will be located in the same sidewall or opposite sidewalls of the vehicle. Depending on the particular type of door system being considered, one or two door operators may be installed over each doorway. FIG. 1, for example, shows one door operator, and the door panel to which it is attached, installed over the left side of the doorway. A second door operator, and the right door panel attached thereto, is likewise installed over the right side of the doorway.
There are various types of door operators in use in the transit industry. Such door operators typically include a motor, some type of drive member and various related components. As is well known in the art, the motor of the door operator can be commanded to rotate in the opening or closing direction. By commanding its motor to rotate in the closing direction, a door operator responds by moving its corresponding door panel to the close position over the doorway, as is shown in FIG. 1. Reference numeral 3 in FIG. 1 is used to denote the door panels in the closed position. The phantom or dotted lines of FIG. 1 illustrate the open position that each door panel assumes when its drive member is rotated fully by the motor in the opening direction. Reference numeral 5 in FIG. 1 is used to denote the door panels in the (phantom) open position.
Although the door operator disclosed in U.S. Pat. No. 5,341,598 operates satisfactorily and is in current use, increased emphasis on equipment reliability and reduction of passenger hazards has created a need for a means of directly holding the door panels in a closed position over the doorway. The invention disclosed herein meets that need by a lock assembly that directly locks the door panel, thereby bypassing intermediate portions of the door operator-door panel structure. The lock assembly disclosed herein further improves reliability in that the door panel is maintained in a closed position, although the primary lock structure has deteriorated or the main drive structure may have failed.